Military chiefs in the US say the country's commitment to Afghanistan has not changed after an earlier suggestion that their combat role might end earlier than previously thought.

Intelligence officials were trying to clarify remarks from Leon Panetta, the US defence secretary, who said that combat operations could end in 2013, a year early.

Speaking before a Congressional Committee, CIA director David Petraeus, once the commander of ISAF and US forces in Afghanistan, said: "The conversation Secretary Panetta had with some press on his plan was more than a bit over analyzed shall we say.

"The policy adopted by the leaders of the coalition, of the ISAF coalition with Afghan President Karzai was that by the end of 2014 ISAF will have transitioned all security tasks to Afghan forces."

Last month, a leaked National Intelligence estimate said the situation in Afghanistan was mired in stalemate.

It reported that the Taliban was not in retreat, and was more resilient and determined than ever to wait out the US withdrawal timeline.

Al Jazeera's Kimberly Halkett, reporting from Washington, says the mixed messages being sent by senior members of the Obama administration are not new.